A. Field of the Invention
This invention relates generally to the fields of histology and cytology, and more particularly relates to a method and apparatus for aspirating and dispensing reagent.
B. Description of Related Art
Reagents are used in a variety of devices in the fields of histology and cytology. For example, one device which uses reagents is a histochemical staining device. Histochemical staining is a useful tool in histological diagnosis and the study of tissue morphology. Histochemical xe2x80x9cSpecial Stainsxe2x80x9d require a series of treatment steps conducted on a tissue section mounted on a glass slide to highlight by selective staining certain morphological indicators of disease states. Typical steps may include pretreatment of the tissue section to facilitate staining, application of various dyes to stain morphological structures, clarifiers to remove unreacted dye, differentiating agents, counterstains, and the like. Each of these steps is separated by multiple rinse steps to remove unreacted residual reagent from the prior step. Incubations are conducted at elevated temperatures, usually around 60xc2x0 C., and the tissue must be continuously protected from dehydration. Other devices that use reagents as part of its processing include Immunohistochemical stainers, devices that perform in-situ hybridization of DNA/RNA, stainers that perform enzymatic tissue stains, and hemtoxylin and eosin (H and E) stainers.
In order to introduce reagents and other fluids during processing, a reagent delivery system and method is used. Typically, the regent delivery system automatically pippettes reagents by inserting a needle or plastic tube into the reagent reservoir or vial, drawing up the reagent into the tube with a motor driven syringe, moving the needle to the slide (or other receptacle) and reversing the syringe to dispense the reagent. Such typical designs have the drawback that the vials are open, exposing the reagent to the atmosphere, permitting evaporation and potentially reducing reagent reactivity due to oxygen exposure. Moreover, open vials are vulnerable to spills resulting in loss of reagent and operator exposure.
The present invention is directed to an apparatus and method for applying reagent to slides for histochemical or cytological analysis. As part of these analyses, different types of reagents are applied to tissue sections placed on slides. The tissue sections are then viewed by a medical practitioner who reads the slide for purposes of patient diagnosis, prognosis or treatment selection. More specifically, the apparatus is a staining instrument that automatically applies chemical and biological reagents to tissue or cells mounted or affixed to standard glass microscope slides. Each slide receives the selected reagents which are dispensed from reagent vials.
Obtaining of reagents is accomplished through a unique reagent dispense system that comprises a probe, a vial insert and a reagent vial. The vial insert is attached to the reagent vial. The vial insert is also contacted with at least a portion of the probe to form a seal wherein reagent is withdrawn from the reagent vial. Dispensing of reagents is accomplished by a probe and a probe dispense and wash station. The probe contacts at least a portion of the probe dispense and wash station to form a seal in order to dispense reagent and in order to clean the probe.
A key advantage of the present invention is to provide a system that aspirates reagents from a vial while minimizing evaporation in the reagent vial.
Another advantage of the present invention is to provide a system that dispenses reagents accurately.
Still another advantage of the present invention is to provide a system that minimizes cross-contamination of the reagent vials through cleaning of the reagent delivery system.
With the foregoing and other objects, advantages, and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several views illustrated in the drawings.